Optical recording media are popularly used for storing and distributing large volumes of content. Examples of optical recording media (optical media) commonly distributed via retail outlets include CDs (compact discs), DVDs (digital versatile disc or digital video discs), HD-DVDs, and BDs.
Several formats of optical media are currently available, including (A) read-only formats such as CD-DA (digital audio compact disc), CD-ROM (CD-read-only memory), DVD-ROM, and other formats wherein content is pre-recorded on the medium, and (B) recordable formats in the form of (i) write-once read-may times formats such as CD-R (CD-recordable), and DVD±R (DVD recordable), etc., or (ii) rewritable formats such as CD-RW (CD-rewritable), DVD-RAM (DVD-Random Access Media), DVD-RW or DVD+RW (RVD-rewritable), PD (Phase change Dual disc) and other phase change optical media. Players that reproduce content recorded on these optical media use a red laser. Optical media, such as HD-DVD and BD (each of which include read-only, recordable and rewritable formats), that can be reproduced with players using a blue laser have also been introduced.
Optical media can be used to store and distribute large volumes of content. For example, a CD-ROM typically has a capacity in excess of 600 MB. Other optical media have recording densities significantly greater than that of a CD. For example, conventional DVD read-only discs have a capacity of from 4.7 GB to 17.0 GB, and HD-DVD and BD discs can store even more content.
Unfortunately, the high capacity of optical media, coupled with recent enhancements to personal computers and the advent of recordable optical media technology, also renders optical media popular for illicit use. For example, unauthorized copying of proprietary and/or copyrighted, recorded content from optical media to optical media on a large scale (also referred to as “piracy”) is a growing concern. The piracy typically entails using software on a computer system having an optical medium drive to copy content from a recorded optical medium onto recordable media such as CD-R or CD-RW (or DVD-R, DVD-RW or DVD+RW) discs.
In addition, theft of prerecorded optical media from retailers, although not widely reported to the public, has received considerable attention from content producers, replicators, retailers, and other parties along the distribution chain, since such thefts occur on a large scale. In the past, retailers have employed different techniques to deter theft of prerecorded optical discs from the retail store. These techniques included, for example, the use of bulky packaging that were difficult to conceal, and/or attaching electronic surveillance mechanisms to optical disc packaging.
While such techniques served to some extent as deterrence, they each have significant disadvantages. Bulky packaging for instance leads to substantial solid waste. Electronic surveillance mechanisms (hereinafter, electronic markers) attached to optical disc packaging were easily circumvented by removal of the optical disc from the point-of-sale.
It has been proposed that miniature electronic markers (such as RF transmitters or transponders) may be directly attached to or embedded into prerecorded optical media. For example, it has been proposed to attach an annular electronic marker including a radio frequency identification (RFID) tag to the center hub of an optical disc. As another example, it has been proposed to embed an electronic marker within a non-readable zone of the optical disc. Electronic markers that are sandwiched in between two substrates or within a substrate of an optical disc have also been proposed. However, such markers prevent theft only if passed thru sensing device. They cannot prevent theft from storeroom or truck.
Several disadvantages exist in current proposals for attaching electronic markers directly to an optical medium. First, the use of electronic markers such as RFID tags remain relatively cost prohibitive. Another disadvantage of current design is that an electronic marker attached to the surface of an optical disc is susceptible to tampering and separation from the optical disc. Further, embedding electronic markers in between two substrates or within a substrate requires substantial and costly changes to current optical disc manufacturing equipment.
Therefore, a need remains for an improved approach for controlling access to prerecorded content on an optical recording medium, that preferably allows such prerecorded optical recording media to be replicated with only minimal changes to current manufacturing equipment, thus allowing existing manufacturing lines to remain substantially intact with only minor adjustments thereto.